Which of the following statements is not correct?

Options

A. Pollen grains of many species can germinate on the stigma of a flower, but only one pollen tube of the same species grows into the style.
B. Insects that consume pollen or nectar without bringing about pollination are called pollen/nectar robbers.
C. Pollen germination and pollen tube growth are regulated by chemical components of pollen interacting with those of the pistil.
D. Some reptiles have also been reported as pollinators in some plant species.

Answer

To solve the question of which statement is not correct, we will analyze each of the provided statements one by one.

### Step-by-Step Solution:

1. **Analyze Statement 1**:
- The statement claims that "Pollen grains of many species can germinate on the stigma of a flower, but only one pollen tube of the same species grows into the style."
- This statement is incorrect because, while pollen grains from many species may land on a stigma, only pollen grains from the same species as the stigma can germinate and grow a pollen tube into the style. The pistil can recognize and reject pollen from different species.

2. **Analyze Statement 2**:
- The statement mentions that "Insects that consume pollen or nectar without bringing about pollination are called pollen or nectar robbers."
- This statement is correct. Insects that take nectar or pollen without aiding in pollination are indeed referred to as nectar robbers or pollen robbers.

3. **Analyze Statement 3**:
- The statement states that "Pollen germination and pollen tube growth are regulated by chemical components of pollen interacting with those of the pistil."
- This statement is also correct. The interaction between the chemical components of the pollen and the pistil is crucial for the germination of pollen and the growth of the pollen tube.

4. **Analyze Statement 4**:
- The statement claims that "Some reptiles also have been reported as pollinators in plant species."
- This statement is correct. While insects are the primary pollinators, some reptiles and other animals can also play a role in pollination.

### Conclusion:
After analyzing all the statements, the first statement is the only one that is incorrect. Therefore, the answer to the question is:

**The first statement is not correct.**